Stoping camera when character is falling.

Well my character goes upwards for my game. Camera is following it there is no problem. But when character is falling, I want to stop camera. I just need to spot maximum reached height

highestPosition =
Pos = target.position.y;
if (highestPosition > Pos) { GetComponent ().enabled = false;}

How can i detect highest position?

You have variables highestPosition , currentPosition.

Now, I would have a check like this

if(currentPosition > highestPosition){
    highestPosition = currentPosition;
}

And then, I would just make the camera follow the highest position. If the player keeps climbing up - the camera climbs together with him. If he falls, the camera stays at the highest reached position.