An adjusting tool having two electrical contacts provides a means for measuring an electrical signal that is used for adjusting electrical parameters of an object as the object is being physically adjusted by the adjusting tool. In an embodiment, the adjusting tool is configured such that the two electrical contacts make electrical contact with electrical contacts of a potentiometer of a hearing aid to receive an adjustment signal that is also applied to circuits in the hearing aid. The two electrical contacts of the adjusting tool maintain electrical contact with the electrical contacts of the potentiometer as the adjusting tool physically adjusts the potentiometer. In an embodiment, the adjusting tool includes a display to provide a visual representation of the adjustment signal as the potentiometer is adjusted.