While the timegrapher device is rather limited in terms of software, the microphone stand that comes with it can be a great addition to a watch timing app. It is well built, allows the watch to be tested in different positions, and has a sensitive contact microphone with an integrated preamplifier.
Here is a prototype adapter box that powers the integrated mic preamp and feeds the amplified signal to the iPhone audio input. No timegrapher device is required, only the microphone.
(click/tap to zoom)
USE AT OWN RISK. Confirm with your specific timegrapher device. Check and match connector pinout, voltage, and polarity. Reverse polarity will damage the preamp!