Ghosts & Spirits is a curious little app for Android that detects paranormal activity around you using various features.
The tool covers many different categories and combines many different types of equipment to turn you into a proper ghost hunter: an EVP recorder, a polygraph that leaves a straight line until it detects a nearby spirit, and radar to locate them on a map.
Besides all this, it includes two more tools that you can enjoy only for a short time before having to pay for the Pro version. These include an EMF meter to locate electromagnetic fields, and a ghost camera to convert what your sensors detect into an image.
None of this is scientifically proven, of course, but you can either use it purely for entertainment or take it seriously depending on your personal beliefs.