

In your home, someone could force themselves in, force you to vote for someone and verify you did so.
With anonymous voting at a polling place, sure someone could force you to go there, but since the vote itself is anonymous (and there’s people around to check it is), they would never be able to verify that you indeed voted X or Y way. It’s also why most countries ban taking pictures of your vote; no proving to anyone how you voted!
You expressly can’t do this. This is why there’s a voting booth and observers who make sure you’re alone in the booth. And after you fill out the ballot, it gets folded inward and placed in a box that is closed off until election day is over. There’s no way to verify who you voted for, as your name isn’t on the ballot.