Why do I see black figures?

I'll just be sitting in my house and see random black figures sometimes. I'll sometimes see little random 'orbs' too. I hear random sounds when I'm home alone, sometimes of the doors upstairs opening and than closing. I don't really hear 'voices', if I do it RARELY happens. I also feel like I'm being watched/someone is with me. Pretty much all the time. No one in my family, that I know, or that's close to me has died. So what's up with all of this?