Static Electricity

Accurately with an "electrostatic voltmeter", "static meter" "static charge meter" or various other test methods (which will give you an indication with varying accuracy).

Try an internet search of the above links, "measuring static charge" or the following link.

http://amasci.com/emotor/voltmeas.html

Reach for a metal object, if your hair stands up on end, you were up there pretty good.