We know you’re not John Constantine, but you just want to find out some occult clues, the following Mr.Ghost EMF detector should be able to meet your requirements.
Mr.Ghost is an innovative portable detector designed to offer you an easy way to electromagnetic field (EMF) around you. As we can see from the images, the EMF detector features ultra compact design, using its integrated 3.5mm audio connector, you can easily connect the EMF detector to your iPhone, iPad or iPod touch, while its free iOS app will clearly show you the position and the amount of the electromagnetic field around you. Apart from that, the EMF detector is compatible with iPhone 4/4S, iPhone 5, iPad 2/3 and iPad 4 as well iPod touch 4G and 5G.
At present, the inventor of Mr.Ghost is raising fund at Kickstarter. Pledging $20 will let you own the EMF detector. If you’re interested, jump to Kickstarter official site for more details.