There's this guy that follows me on Twitter, he's cool. But he's a Computer Science major, and he is a little weird. Sometimes I wonder if he can hack me. If you take Computer Science do you think someone would be smart enough to know how to hack? Is there anyway I can know if he does it?
Answer on Can you hack someone if they are following you on Twitter?
The short answer is no.
The long answer is, with enough knowledge and enough time, one can do just about anything - though the example you give is highly unlikely due to security measures taken by Twitter to protect user identity.