An electroscope can be used to detect whether a body is charged or not. The following figure shows a simple electroscope.

In an Electroscope, two metal foils (here Aluminium foils are shown) are hanged with the help of a conductor in a glass jar with a lid. When a charged body touches this conductor, its charged gets transferred to the metal foil and they move apart due to like charges. This shows that an electroscope detects charges.