how to calculate time intervals in unity,how to time a time frame in unity

I’m doing a free fall environment in unity and I need to calculate time intervals so that I can calculate the speed of the object at the time it passes through different points in the scene. Please Someone help me!!!,I’m doing a free fall environment in unity and I need to calculate time intervals so that I can calculate the speed of the object at the time it passes through different points in the scene. Someone please help me!!

Time.deltaTime