Preferably someone with experience in contacting whatever/whomever it is, and finding out what it wants? Sometimes it only takes a simple action to satisfy a wandering spirit so they either don't bother you any more, or to move on to the spirit world, which is where spirits are supposed to go after physical incarnation is over.
Persons much more knowledgeable than me say that simply exorcising it could send it/them into a nearby building, where it could start bothering people who don't have any clue how to deal with it.
On another front, try to find out exactly where it entered your home or property. Supposedly spirits leave an energy trail when they enter a place. You could try dowsing to find where that was. The idea is to send the energy back out the way it came, and 'close the door', as it were. Salt is supposed to repel spirits of the dead. You can sprinkle it around the edges of your dwelling (inside and outside, if possible). At least salt does not smell like pot. 
I have also read that filling your home with light and good vibes (play some music that you like, maybe), can help get rid of troublesome spirits/negative energy.
If nothing else, be very clear that your unwanted intruder is NOT welcome to stay. We do not have to put up with being bothered by spirits, anymore than we would be expected to open up our door and let whoever wants to come in and stay.
Good luck, and invoke help from whatever higher power you believe in to bring you peace and safety. 
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