So you want to turn your regular watch into a smartwatch? The Chronos Smart Disc has you covered. Just attach it to the back of your watch to start getting notifications and fitness tracking. You can control your phone from the watch. For instance, you can take a quick photo, silence calls, and control your music.
There are no magnets involved here. Just attach the gadget with micro-suction, and you are ready to go. You can also swap Chronos between watches easily.