You can change from CM to IN, from the program. This is a very simple project to implement with U1.
You can always make it more hard! On U1 there is a clock and an SD card, so you can use them to make a distance logger.
One other idea is to use the ESP8266 plug on U1 (WIFI module), and you get an email alarm if the distance is changing, or to log the distance on thinkspeak.