Where do you find voodoo doll my sims kingdom?

After you have unlocked the seance scroll, then you can randomly get the essence while two or more people are participating in the seance. Other than that, i think if you scare the people on spookane, they may give you a voodoo doll...

You can also dig by the Bridge to get voodoo dolls, same with jade and dead wood

And you can get them in a coupple treasure chests