Camera.ScreenToViewportPoint

Description

Transforms position from screen space into viewport space.

Screenspace is defined in pixels. The bottom-left of the screen is (0,0); the right-top is (pixelWidth,pixelHeight). The z position is in world units from the camera.

Viewport space is normalized and relative to the camera. The bottom-left of the camera is (0,0); the top-right is (1,1). The z position is in world units from the camera.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Update()
    {
        transform.position = Camera.main.ScreenToViewportPoint(Input.mousePosition);
    }
}