There are basically two types of hacks: flying and autohit. To deal with a flying hacker you can get him close to the ground and kill him (it will be easy if they dont have autohit). The flying hack is very unstable so you can fire at them with a bow (there's a chance they will fall, and if they hit the ground they will mostly die immetiadely). Autohitting hackers are harder to defeat. If you get in their range, they will hit you with everything they're holding, even when they're looking another way. You may need a teammate to kill him in pvp (thats why teams of 2 is the best to deal with them, two hackers together are very rare. You can always make a trap when you can hit the hacker and he can't hit you or push him into the void (if he doesn't have the flying hack too, he's dead).