How about a laser on a servo, mounted so that it will point onto the desk but off to the side, with a hotkey to activate it? Then when the cat wants to climb o

How about a laser on a servo, mounted so that it will point onto the desk but off to the side, with a hotkey to activate it? Then when the cat wants to climb onto the keyboard, you press the hotkey to give it something to chase that is not on the keyboard.