How to detect button pressed and kept down and button up in Tkniter GUI?

You can bind all of these events to specific functions as callbacks. You can map one function for when the button is pressed and another for when it is released.

In the example below I have mapped each of the buttons to the mouse press and release buttons, each of them pass their respective character representations as parameters. Additionaly There are two bindings for keypress and keyrelease which also maps to two functions these functions check to see if the key pressed was an ‘A’, ‘S’, ‘D’, or ‘W’ and if it is then it passes them to the mouse move buttons since those two commands should be the same whether it is the mouse clicking the w or the keyboarding pressing the w. I left the stop button for you to do.

import tkinter
import tkinter.messagebox
import customtkinter

# Setting up theme
customtkinter.set_appearance_mode("Dark")  # Modes: "System" (standard), "Dark", "Light"
customtkinter.set_default_color_theme("blue")  # Themes: "blue" (standard), "green", "dark-blue"


class App(customtkinter.CTk):
    def __init__(self):
        super().__init__()

        # configure window
        self.title("Cool Blue")
        self.geometry(f"{1200}x{700}")

        # configure grid layout (4x4)
        self.grid_columnconfigure(1, weight=1)
        self.grid_columnconfigure((2, 3), weight=0)
        self.grid_rowconfigure((0, 1, 2), weight=1)
        self.bind("<KeyPress>", self.key_pressed)
        self.bind("<KeyRelease>", self.key_released)

        # create sidebar frame for controls
        self.sidebar_frame = customtkinter.CTkFrame(self, width=200)
        self.sidebar_frame.grid(row=0, column=0, rowspan=4, padx=(5, 5), pady=(10, 10), sticky="nsew")
        self.sidebar_frame.grid_rowconfigure(4, weight=1)

        self.logo_label = customtkinter.CTkLabel(self.sidebar_frame, text="Controls",  font=customtkinter.CTkFont(size=20, weight="bold"))
        self.logo_label.grid(row=0, column=1, padx=20, pady=(10, 10))

        self.button_up = customtkinter.CTkButton(self.sidebar_frame, text="W", height=10, width=10)
        self.button_up.grid(row=1, column=1, padx=20, pady=10, ipadx=10, ipady=10)
        self.button_up.bind('<ButtonPress-1>', lambda x: self.motion_event_start(x, 'W'))
        self.button_up.bind('<ButtonRelease-1>', lambda x: self.motion_event_stop(x, 'W'))

        self.button_down = customtkinter.CTkButton(self.sidebar_frame, text="S", height=10, width=10)
        self.button_down.grid(row=3, column=1, padx=20, pady=10, ipadx=10, ipady=10)
        self.button_down.bind('<ButtonPress-1>', lambda x: self.motion_event_start(x, 'S'))
        self.button_down.bind('<ButtonRelease-1>', lambda x: self.motion_event_stop(x, 'S'))

        self.button_left = customtkinter.CTkButton(self.sidebar_frame, text="A", height=10, width=10)
        self.button_left.grid(row=2, column=0, padx=10, pady=10, ipadx=10, ipady=10)
        self.button_left.bind('<ButtonPress-1>', lambda x: self.motion_event_start(x, 'A'))
        self.button_left.bind('<ButtonRelease-1>', lambda x: self.motion_event_stop(x, 'A'))

        self.button_right = customtkinter.CTkButton(self.sidebar_frame, text="D", height=10, width=10)
        self.button_right.grid(row=2, column=2, padx=10, pady=10, ipadx=10, ipady=10)
        self.button_right.bind('<ButtonPress-1>', lambda x: self.motion_event_start(x, 'D'))
        self.button_right.bind('<ButtonRelease-1>', lambda x: self.motion_event_stop(x,'D'))

        self.button_stop = customtkinter.CTkButton(self.sidebar_frame, text="Stop", height=10, width=10)
        self.button_stop.grid(row=2, column=1, padx=10, pady=10, ipadx=10, ipady=10)

        # create Video Canvas
        self.picam = customtkinter.CTkCanvas(self, width=800, background="gray")
        self.picam.grid(row=0, column=1, rowspan=2, padx=(5, 5), pady=(20, 20), sticky="nsew")
        self.picam_label = customtkinter.CTkLabel(master=self.picam, text="Live Video", font=customtkinter.CTkFont(size=20, weight="bold"))
        self.picam_label.grid(row=0, column=2, columnspan=1, padx=10, pady=10, sticky="")

        # create sidebar frame for Environmental Variable
        self.measurements = customtkinter.CTkFrame(self, width=200)
        self.measurements.grid(row=0, column=3, rowspan=4, padx=(5, 5), pady=(10, 10), sticky="nsew")
        self.measurements.grid_rowconfigure(4, weight=1)
        self.label_measurements = customtkinter.CTkLabel(master=self.measurements, text="Environment:", font=customtkinter.CTkFont(size=20, weight="bold"))
        self.label_measurements.grid(row=0, column=2, columnspan=1, padx=10, pady=10, sticky="")

    def key_pressed(self, event):
        if event.char and event.char in 'wads':
            self.motion_event_start(event, event.char.upper())
        elif event.keysym == 'Left':
            self.move_left_arm_function()
        elif event.keysym == 'Right':
            self.move_right_arm_function()

    def key_released(self, event):
        if event.char and event.char in 'wads':
            self.motion_event_stop(event, event.char.upper())
        elif event.keysym == 'Left':
             # do something
        elif event.keysym == 'Right':
             # something else

    def motion_event_start(self, event, button):
        print(f"{button} Pressed")

    def motion_event_stop(self, event, button):
        print(f"{button} Released")


if __name__ == "__main__":
    app = App()
    app.mainloop()