canvas.z = z + 1

 from tkinter import *
tk = Tk()
z = 1
canvas = Canvas(tk, width=400, height=400)
canvas.pack()
x = canvas.create_text(150, 100, text = z)
def y(event):
    global z
    if event.keysym == 'Up':
        z += 1
        canvas.itemconfigure(x, text = z)
        tk.update()
canvas.bind_all('<KeyPress-Up>', y)
tk.mainloop()