Centrifugal is not a real force. It's just the equivalent of the force needed to be applied to overcome inertia as per Newton's second law. When a body is moving in a circular path with constant speed, its velocity is constant in magnitude but not in direction. Thus the rate of change of velocity is not zero. As the body keeps changing direction and has non-zero acceleration, there must be some force acting on it.
Let's assume a body of mass m moving on a circular path of radius r. The body moves by a small angle dθ in time dt. Distance traveled by the body during this time is given by the product of the radius of the circle and the angle subtended at the center that is rdθ. Therefore dt can be written as
Centrifugal force is oriented along the negative y-axis as per the assumed coordinate system which is the direction towards the center. So whenever the body is revolving in a circular motion with constant speed, a centripetal force towards the center is required to provide for the inertial force. Centrifugal is not one of the four fundamental forces or derived from them unlike centripetal force rather it is the result of newton's second law.
As a body in circular motion has acceleration towards the center, the person inside the body experiences a pseudo force in opposite direction i.e. radially outward. It is just like a person inside a lift moving upwards experiences a downward pull. This phenomenon leads to the common misconception that centrifugal force is something special force acting radially outward.