The most common control signal for bioelectric control of prostheses is the electrical activity of the muscles. But the use of surface electromyography signals has several disadvantages, these are electrical interference and noise, which have a higher amplitude than the original signal. Therefore, this paper presents a technique called optomyography as an alternative to accurately measuring muscle activity. Optomyography measures skin surface displacement occurring due to muscle contraction with the help of a near-infrared photoelectric sensor consisting of a light-emitting diode and a phototransistor. The main purpose of this work is to study the methods of receiving, processing, analyzing signals and determining the signal–force calibration curve obtained for the sensor. To read the signals, an armband with built-in sensors was made during the study. We tested the method of near-infrared spectroscopy as a method that allows us to look at muscle phenomena in a different way, and proved that optomyography signals can be used to recognize movements, obtain information about muscles at different depths, and determine the grip strength.