Quantity   Component name
1 × android smartphone any android smartphone (you probably want root)
1 × 4-pin headphone cable just cut open some headphones
1 × 1M resistor probably can have other values, used as "dummy microphone"
1 × reed switch I got mine from some cheap speedometer, if you have 3D printer or similar, you can print the "case" yourself
1 × software something something Linux is not realtime enough? might need to try with a larger diameter wheel