There are plenty of Ultrasonic Rangefinder Modules available on the market, here's one way to build your own.
The How It Works portion of the Build Your Own Ultrasonic Rangefinder Project is now available in PDF. All you wanted and didn’t want to know about ultrasonic rangefinders can be found within. The Quick Start Guide is found at the beginning, the How It Works section is begins halfway through the PDF.
Construct the circuit seen in the Kemani/Analog Front End Schematic.
Connect the TX_TRIGGER line to Arduino pin 4. Connect RANGE_PWM to Arduino pin 9. Connect the GND line of the breadboard to the GND connection on the Arduino. (Ppower, GND)
Connect an external DC power source to power jack J6 of your Kemani or Amani64.