from tkinter import *

window = Tk()

window.title("Welcome to Tkinter!")
window.geometry('400x300+30+200')

def checkEvent():
    if chk_state.get():
        chk.configure( text='Checked' )
    else:
        chk.configure( text='Un_checked' )
        

chk_state = BooleanVar()
chk_state.set(True)  #set check state
chk = Checkbutton(window, text='Choose', var = chk_state, command = checkEvent)
chk.grid(column=0, row=0)


window.mainloop()