find the exact point on which a projectile will hit enemy

Hey everybody. I was just wondering if there is anyway to find the exact point on which a projectile will hit the enemy (head, lung, or other parts). In my game the enemies are far far away so the player has to aim above the enemy to hit him. I,m using rigidbody and addforce for my projectile motion, and plus raycast is not possible as raycast move in straight line. I want to find it as soon as the projectile is launch or even before it actually hit the enemy. Thanks in advance