How can I scale gameObject by two point?

How can I scale bowstring model by two point (one point is my finger point,other is binded at bow) when I archery?

I'd put the pivot point of the bow at its extreme front (where the arrow is stuck before launch) and so I'd have the base for a correct stretch of the mesh. Then I would play with scale parameters to obtain the effect. In example, if the front axis is Y, I would increase it slowly to charge the arrow, and squish down X to compress the bow, then... well, I think you understood. This is the easiest way, I think.

An alternative might be to do this motion as an animation on the model, and just make sure Loop and Play Automatically is set to false. On drawing the bow, play the animation [animation.Play()]. Then on release, go back to first frame [animation.Rewind()]

Thanks everybody,I have solved this question with LineRenderer.