Can my iPhone indicate when I am not wearing my Watch?

I have become very dependent on the sleep data which my watch provides. But I often charge it up late in the day (so that it has battery throughout the night) and then sometimes forget to put it on before going to bed. I would be wonderful if this screen ...

... could indicate when my watch is not on my wrist. There seems to be plenty of space available.

Would a simple JAVA app be able to do what I want?

Thanks, Bob