The process of recording an actor’s movement digitally for the purpose of animating a digital character in a movie is called realistic animation motion capture cgi (computer generated imagery) performance animation

It is called Motion Capture.

Explanation:

Motion capture it's a widely used technology that allows us to record (or capture) the movements of a real person, and convert them to a digital environment.

It can be used in the development of video games when facial expressions or realistic movements are needed to bring fictional characters to life, motion sensors are used on a real person, and the person displays the necessary emotions, movements or expressions that are later digitally adapted to the 3D character.

Motion capture was one of the main techniques used to bring the famous Thanos, the famous Avenger's villain to life. Josh Brolin, the actor, would perform almost every scene wearing a specialized suit to capture the movements and facial expressions that were introduced to the 3D rendered Thanos model.