You could use the “Manifacturer Specific Data” Bytes in the BLE Standard to send some Data Between Wearable and phone.
You could use the watch as a sort of beacon that can send your data in the portion of the message. Then you could read those values and get the data. Note that you can only encode 31 bytes in the Manifactuer Specific Data Section in the standard bluetooth spec and that you can only read the inputs every time you can recieve the bluetooth beacons.
You can see the BLE Spec here. For your Data you could use the Payload.
You would have to scan for the ble beacon permanently and get the newes payload information.