The ever-present desire for progress is represented in all forms of human activity, especially when it comes to testing the limits of the human body. An electronic device to measure reaction time to sound stimuli was described, developed, and build in this final paper. Reaction detection is realized with the help of an Inertial Measurement Unit (IMU), which consists of an accelerometer (for measuring acceleration in three coordinate axes x, y, and z), a gyroscope (for measuring angular velocity in three axes), and optionally a magnetometer (for measuring Earth's magnetic field in three axes). By using a commercially available MPU6050 type inertial measurement unit, a prototype with the ability to detect movement was developed. The prototype is based on the NodeMCU V3 microcontroller which enables the display of detection results on a connected computer or mobile phone via WiFi communication and web page generation. The code of the prototype was written using the Arduino IDE environment. For the prototype, an enclosure has been designed using the SolidWorks software package and created using 3D printing technology. A printed circuit board was designed using the platform Altium Designer. The PCB integrates the microprocessor of the microcontroller and the inertial unit of the sensor module used to build the prototype. The device testing has been conducted by mounting it on a punching bag using elastic adjustable bands in order to check functionality.