My laptop has a sensor that can detect how far the hinge is bent. This is because it can turn 360 degrees. The accelerometer is in the display, keeping the display up right and rotating the body past 180 degrees, it switches to tablet mode. This isn’t done with classic magnets in the display and body and it’s not using the accelerometer as I can read the accelerometer data to know it stays in place, the hinges themselves must know the angle at which they are bent. It also changes mode again when it’s fully opened 360 degrees.