You absolutely can. By voting for someone who has no chance of winning. It’s purely a thing to make you feel good about yourself. And no one will know either. You could claim you voted for Cornel West but actually vote for Trump and no one will be able to say you were lying.
I’m never going to get what I want, so I vote pragmatically. And stopping the guy who literally says he’s going to be a dictator seems like a pretty fucking important thing to do.