According to Gurbani, evil and good spirits do exist. In the tenth ashtpadi of Siri Sukhmani Sahib, Guru Sahib has described the creation of Vaheguru and in that He has written the following verses:
KAYEE KOT JAKHIYA, KINNER, PISHAACH||
KAYEE KOT BHOOT PRET SOOKAR MRIGAACH||
Padd-arth:
Kayee: Many
Kot: 10 million
Jakhiye: Kind of demigods who are ruled by Kuber devta. A very interesting tale in Mahabharata exists where the Jakhiyes beat the Kauravs and the Kauravs were then saved by their enemy and cousin – Arjun.
Kinner: Kind of demigods with head of a horse and the body of a human.
Pishaach: The extreme kind of evil spirit – extreme kind of bhoot.
Pret: One level up from bhoot but a level down from a Pishach.
Bhoot: A ghost, an evil spirit.
Sooker: A dirty pig
Mrigach: One that eats a deer i.e. a lion.
The whole pankiti means that there are countless demigods, evil spirits, dirty animals and flesh eating animals.
Based on this pankitis and after reading several other pankitis in Gurbani it is safe to say that such evil spirits to exist but a Sikh has nothing to do with such evil practices. A Sikh is the worshipper of Vaheguru and does not bother about any evil and as such no evil bothers or comes near a Sikh.
Daas,
Kulbir Singh