How To: Detect and Keep a Potential WiFi Hacker Off My Network?

lately, I've been having some difficulty with my network. After recognizing a few signs (becoming de-authenticated and such), i figured someone was, and still possibly is, trying to hack my network. if there a way to detect someone trying to hack my network, and if there is, is there a way to boot him off permanently? also, i wouldn't mind giving this person a little present wink wink but I know hardly anything about hacking myself or much less, getting the guy's IP address. any help would be greatly appreciated and welcome. thank you all for your time.