Your smartwatch is also recording your PIN

That's pretty good and precise motion tracking
https://www.engadget.com/2016/07/06/your-smartwatch-is-also-recording-your-pin/

Personally I've never used my watch-wearing hand to enter the PIN and I suspect that'll hold true for most people, especially with the smartwatch since you're more likely to want to use your dominant hand for watch interactions (and also PIN entering). But I still find it interesting that the probability of reconstructing the PIN is so high.