You never saw the neon tester pen? They typically have a small screwdriver on one end and a pocket clip. The clip is the "ground" and you are the ground electrode system, capacitively coupled to the earth. There is a megohm resistor there so you won't see circuit current. If you touch the screwdriver to a hot lead, the neon lights. Sometimes you just have to be close to the hot lead. They may not light 100% of the time, particularly if you are very well isolated from ground, like up in an attic on dry truss chords but they usually work OK.
I will root around and see if I can come up with one.
