While there is a hidden diagnostic port it requires access to a special accessory which for obvious reasons apple does not sell to consumers. Theres a 6 pin port in the watch case thats normally hidden by the watch strap.

Apple Watch Wikipedia
Apple watch secret port cable. Every apple watch has a secret port hidden beneath its bottom band and it turns out the port could be pretty useful. A redditor however seems to have gotten his hand on this accessory. Except the charging cable comes with the apple watch people also found other ways to charge their watch without this charger. This cable is way more exciting than that secret apple watch port yet another lucrative new sector of the enterprise market is being opened up for apple thanks to redparks latest innovation. Tucked inside the apple watch is a little secret if you know where to look. Apple watch owners may have noticed theres a tiny port hidden inside the groove of the bottom band connector.
Ive been looking around the internet for a long while and unfortunately i found nearly nothing to help me find a way to make the lightning cable accessible to the apple watch. Slide off the apple watchs bottom band peek into the connection slot and youll find there is a hidden port that apple doesnt acknowledge to public. The apple watchs port is for. Before the watchs release there was some speculations whether the port just be used. One accessory maker claims this six pin port can in fact be. Remove the strap on the button side of the apple watch case.
Discussion pin out information of the apple watch diagnostic port. Suggested by umg bryan adams shine a light. From the patents here it is clear that such a tool does exist. Place the sewing needle in the port hole. The first answer is that you charge it with a charger made to fit that port if you can find any such thing. While apple isnt saying what its for its likely hidden away and covered up.
Category science technology. How do i charge an apple watch with the hidden port i have two answers to this though the second is more of a question. Dont press the needle to access that door like you would to open the sim card tray on an iphone. Song everything i do i do it for you. The apple watch does not come with any physical port that you can use to connect it to a computer.