In this work we describe a simple setup for measuring electrostatic charge and polarity in electrostatic experiments. This low-cost detector only requires a graphite pencil, a capacitor, two switches, and a voltmeter, and holds the promise of transforming qualitative activities that are commonly used to teach electrostatics into quantitative activities. In order to measure the charge and polarity of charged objects, a pencil is used as an antenna to collect charge from the object under study. The collected charge is transferred to a capacitor, and the resulting voltage at the capacitor is measured using a voltmeter. In contrast to other devices, our detector can be used to measure the amount of charge stored in objects at several thousand volts, as for example Van de Graaff domes.