The IEC Coulomb Meter is a useful tool and behaves similar to a "digital electroscope".
The display will show the number of coulombs deposited into the instrument either by current through a resistance or from a capacitor or from a source of static electricity .... for example,  a charged plastic rod.
An Electroscope will deflect its vane,  but this instrument displays the charge digitally in coulombs up to 1.999 nano coulombs.