from tkinter import *
root = Tk()
off_color = "red"
on_color = "green"
def on_check():
    if cbVar.get() == "1":text["fg"] = on_color
    else:text["fg"] = off_color
cbVar = StringVar(root)
cbVar.set(0)
chbox = Checkbutton(root,variable = cbVar,text="Check me",command=on_check)
chbox.place(x=0,y=0)
text = Label(root,text="This is a text",fg=off_color)
text.place(x=0,y=50)
mainloop()