Diagrams and Code at: https://www.elithecomputerguy.com/2019/06/hc-sr04-ultrasonic-distance-sensor-audio-alert-with-arduino/

With an HC-SR04 and a Piezo Buzzer you can create an audio distance sensor like the one many cars have for backing up.

Functional Parts in the Project:

Arduino Uno – https://store.arduino.cc/usa/arduino-uno-rev3
HC-SR204 Ultrasonic Sensor – https://amzn.to/31AGgYC
Micro Breadboard – https://amzn.to/2XbFX7w
Piezo Buzzer – https://amzn.to/2F961py