Spying on computer need help?

i feel like somebody is spying on my computer but I can't verify it. I have very good reasons bec 1. when I get home, my work area looks doesn't look the same. Definitely not a family member, more like a neighbor ( I live in an apt). I have some important files ( banking, family pics etc) and I don't what it jeopardized. Is there a way I can figure out if iam being spied on?( email, key loggers etc).