IP Address

I was wondering, can someone hack into your IP Address to track you down? Or is that considered against the law by Invasion of Privacy? I live in the United States. How does one track an IP signal anyways, if you pull the modem cord out of the modemjack, will the hacker not be able to get into your computer or can he still reroute somehow? I am very worried on this subject because i think someone has hacked into my computer somehow, maybe I’m just paranoid. Please E-Mail me back with the answer at Prowler_9@go.com