If you hold that thing up to your ticket, you'll lose your ticket. And then what will you do? The conductor will ask for your ticket, and you won't have it. And that's it, you're caught, you're in trouble. They'll kick you off the train and take you to the police station, and we won't be able to travel with you, and I'll be bored. But you won't be bored at all with the police, believe me.
Never hold something that looks like a key fob, used to open building entrances, up to your ticket. Never.