Go to Settings > General > About. To the right of "Model Number", you can see the Device Number (M number). To see the the Model Number (A number) tap on the device number.
Find the serial number, EMC number and model number printed on the underside of your Mac near the regulatory markings. It's also on the original packaging next to a barcode label. EMC is the most accurate number to compare with our list as it takes into account the year of your device.
The original packaging might also show an Apple part number such as MNYF2xx/A ("xx/A" is a variable that differs by country or region and is not included on our list so can be disregarded)."
Go to Apple icon > About this Mac > System Report. It will automatically be selected on the hardware tab (left side). To the right, the model name and model identifier will be written on the first two lines."
To find out what model watch you have, turn your watch on