So from the legislation, it would depend on whether:
1. A smartwatch is a "hand-held device" for the purposes of the legislation
2. If so, whether it is a device "which performs an interactive communication function by transmitting and receiving data" (pretty obvious it does)
3. If so, whether the behaviour in the OP counts as "using" it for the purposes of the legislation
It would need to be tested in law, and even then only at Crown Court to get anything binding.