Several new technologies to capture motion, gesture and forces for musical instrument players’ analyses have been developed in the last years. In research and for augmented instruments one parameter is underrepresented so far. It is finger position and pressure measurement, applied by the musician while playing the musical instrument. In this paper we show a flexible linear-potentiometer and forcesensitive-resistor (FSR) based solution for position, pressure and force sensing between the contact point of the fingers and the musical instrument. A flexible matrix printed circuit board (PCB) is fixed on a piano key. We further introduce linear potentiometer based left hand finger position sensing for string instruments, integrated into a violin and a guitar finger board. Several calibration and measurement scenarios are shown. The violin sensor was evaluated with 13 music students regarding playability and robustness of the system. Main focus was a the integration of the sensors into these two traditional musical instruments as unobtrusively as possible to keep natural haptic playing sensation. The musicians playing the violin in different performance situations stated good playability and no differences in the haptic sensation while playing. The piano sensor is rated, due to interviews after testing it in a conventional keyboard quite unobtrusive, too, but still evokes a different haptic sensation.