In order to monitor targeted individuals, electromagnetic waves are also used, at least partial. I have my measuring device just one day, but could already measure an extremely high load of micro tesla (µT) in front of my computer (normal values for example here: http://www.emfs.info/sources/levels/thresholds/). I have the device only one day, because the attacks on me with EMF weapons started in January 2017. Before that I was only ganggestalked. Every Targeted Individual should get such a device for sure. I bought mine at German Amazon (https://www.amazon.de/elektromagnetische-Strahlungs-Detektor-Prüfvorrichtung-elektrischen-magnetisches/dp/B01CZFF97G/), comparatively cheap. There are certainly better devices on the market.