Sensors that can measure current stepper motor position

Hi guys, what sensor module can measure the position of stepper motor? Let's said I programmed the stepper motor to move 87 degrees but I'm not sure whether the stepper motor did lose steps or not so I wanted to read the correct steps of stepper motor has moved. What sensor can I used to do this?

Rotary encoder.

But if you miss steps, or think you may miss steps, what you really need is a stronger stepper.

Or you can fit a stop and drive the motor into that - then you know where it is .