I’ve got one of these at home and had no real idea what to do with it since it lacks wifi. However if has a couple of buttons and XYZ sensors, as well as some LEDs so it’s potentially interesting. Anyone discovered the post below which describes booking it up to a pi, and therefore it could be added to HA. Uses include as a control or sensor node.
http://www.suppertime.co.uk/blogmywiki/2017/08/microbit-controlled-radio/