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.
Upload the ArdRanger code to your Arduino. Do not start the Serial Monitor.
Construct the circuit seen in the Kemani/Analog Front End Schematic.
Connect an external DC power source to power jack J6 of your Kemani or Amani64.