CODE EXAMPLE FOR CSHARP

unity mouse button names

void Update()
{
    if (Input.GetMouseButton(0))
    {
        Debug.Log("Left Mouse Button Down");
    }

    if (Input.GetMouseButton(1))
    {
        Debug.Log("Right Mouse Button Down");
    }

    if (Input.GetMouseButton(2))
    {
        Debug.Log("Middle Mouse Button Down");
    }
}