If you think you may have ghosts in your house or are just interested in ghost hunting, a one piece of equipment you will need is an EMF meter. EMF stands for Electromagnetic Fields, this piece of equipment it is possible to locate and track energy sources. This energy in turn creates a disturbance in the EMF field allowing your EMF meter to detect their presence.
Their indicators on an EMF detector are usually calibrated in milligauss. In absence of moving magnetic field, an ideal meter will read 0 milligauss. Uncalibrated meters often read slightly off zero. Industrial EMF Detectors will often read 2-3 milligauss when placed in an open field not near, for example, power lines.
When using for Ghost hunting make sure to take notes of all the appliances and any other sources that would let off an Electromagnetic field because these sources will spike the EMF detector and give you a false reading, so it's important to keep their location as you log your results.
Be aware of what a reading that suggests paranormal activity looks like. If you log a reading that registers between 1.0 and 8.0 on the EMF meter, you may be in the presence of spirits. Paranormal activity will normally register in the range of 2.0 to 7.0 milligauss, the higher the number the more you will know if you are in a presence, also take your reading in places where the site of which paranormal activity is unlikely and let this will serve as your baseline reading first.
Now with your EMF detector, scan the area with a back and forth, and up and down motion in the area where you are investigating. Do this in a gentle even pattern. Never jerk the meter.
While you are scanning have another person walk with you with a camera, if you get a high reading start taking pictures, point the camera in the same area where the high EMF reading was caught.
The best time for ghost hunting is anywhere from 9pm to 6am, these are the psychic hours, but anytime can produce results. Photos have historically been better in the dark but don't let that stop you from taking them during the day also.
Electromagnetic field detectors are very useful tools in ghost hunting provided they are used properly. Make sure you read the instructions carefully or have someone near but that is experienced in the usage of EMF detectors.