I think there are ghosts in my house?!?

Okay so I haven't actually seen them but my Mother was just talking about her "experience" with them. So first she says when its really late and shes on the computer or something she can see "a figure" out of the corner of her eye. But of course when she turns her head its gone. Also things from her dresser fall off on the floor and she doesn't even bump it or anything. And that actually happened to me today too. I was borrowing her computer and out of nowhere a can of hairspray I think just falls on the floor and I didn't even touch it. Also when its really late and she has to use the potty or something she can hear creaking or tapping and she gets annoyed with it and says "knock it off" to whoever or whatever was doing it and she says it stops when she says that. I know a few years ago the couple who owned this house died, so maybe its them? It wasn't like 100 years ago or anything it was in the 2000s when they died my mom says. But then their son got the house like 5 years ago and then we got it about 2 years ago. I haven't had any experiences with these "ghosts" but its kinda starting to freak me out cuz I still don't know why that thing fell off her dresser just out of nowhere so it could be ghosts... So anyway I need like a ghost expert or something to tell me if there are actually ghosts in my house and what can I do to make them like... not come near me?