I bought a pair of Adidas basketball shoes, took out the insole, found a hole under it, put something in it, and checked that it was micoach. What is this?

Adidas miCoach stride sensor-Adidas running shoes with miCoach slots, such as adiStar and Supernova, are directly clipped on the shoelaces or placed under the insole of the left foot.

Wait; The stride sensor provides you with unique detailed data such as stride frequency, distance and pace, and sends the information back to miCoach Pacer.

There is a groove under your sole, that is, the insole, where you can put the stride sensor. So you need to buy your own stride sensor.