Are there ghosts or evil spirits hovering over our heads? Can they cause us harm at will?
Ghosts are an invention of the human imagination. They have no substance, and they do not have anything to do with us. They simply do not exist.
God has given us some information about the jinn, a type of creature given the same measure of free will as human beings. They are required to believe in the divine message given to Prophet Muhammad, peace be upon him, as they were required to believe in the message given to Prophet Moses, peace be upon him. Like humans, most of them do not believe. Those of them who believe are good ones, and those who turn away from faith are bad ones, or Satans.
Their world is different from ours. They do not harm us as we do not harm them. We cannot see them, although they see us.