It's not too difficult, but there are a lot of things that would need to go into a design.
What is the thing that you are detecting the height of? Do you mean the voltage, a fluid level, the altitude?
Do you have a power supply? Do you have a buzzer?
How do you want the circuit to be re-armed. When the "height" is too much, the buzzer sounds, then it is reset. After that, what has to happen for the buzzer to sound again?
I am detecting the height of a chair frame to make sure its not too high or two low. I plan on using two sensors with light beams that when broken set off a buzzer. I guess I can use a latching relay to keep the buzzer on until I push a button to turn it off? I will probably use a24v power adapter for power.
A small SCR is an alternative solution than a relay. You circuit wold trigger it on and you would use normally closed push button to reset it. I was thinking of something like a 2N5060. You need an SCR with a currrent rating greater then the buzzer current and a holding current rating less than your buzzer current.