I believe in the existence of Jinn (as per Quran and Hadith). Is there any existence of badd-roh ie evil spirits? Is it true that if a guy is killed then his roh can harm or scare people? What about Ham-zaat or witch? Can Jinn harm people? Can they scare us to eg leave our house (or the house they were living in and we have bought it)?This is an important question so please response with some reference from Hadith too.

As Quran said Jinn are also makhlooq of Allah
Aim of creation is worship

Ref: Holy Quran 51:56