There are many paranormal investigators in the world and many of them are very successful in their field. A successful paranormal investigator is not one who uses the most complicated tool or try to detect paranormal existence scientifically but a successful investigator is one who, who can find out the existence and one who believes that ghosts exist in the world and accepts their existence.
There are many scientific tools to detect paranormal activities but there is no scientific explanation for the existence of ghosts in the world. The greatest tools are the embedded within our own personality.
According to people who believe in ghosts, ghosts are those people whose soul has not moved to heaven even after their death due to certain reasons. Ghosts are called as spirits of human beings who still retain their emotions in this world even after their death. No one knows if ghosts are the spirits of humans then why they react in a scary way.
The activities or the existence of ghosts still does not have a scientific explanation. There are researches going on about the existence of ghosts in the world. Still scientists does not believe that there exists ghosts in the world though technology has found out many ways to detect them