Charging an iPhone with a watch charger is not as difficult as it seems. First, make sure that the watch charger is compatible with your iPhone. If it isn’t, you can buy one that is. Next, plug the charging cable into the wall and into your iPhone. Turn on your iPhone and wait for the indicator to light up. Once it does, plug in the watch charger and turn on your iPhone again. The phone will now be charged and ready to use.