Alarm sound detection

I have a bluetooth bicycle lock with an alarm buzzer system. I want to send a signal to the arduino when this alarm goes off. I wanted to what kind of sensor i can use for this case. Also, i have tried using the sound sensor but it does not specifically detect the alarm sound. I want a solution which will uniquely identify the alarm sound and ignore the background noise.

I want a solution which will uniquely identify the alarm sound and ignore the background noise.

That is a great deal more difficult than you can imagine. I would think it is outside the possibilities of an Arduino to do it to the degree of accuracy you would like.

Can you break out the electrical signal that powers the buzzer?

If you can identify a specific frequency and sound level is considerably above the background noise, it should be possible. A microphone input, band pass filter and level detector circuit might do it.