Driving distance sensor from ubuntu usb
I would point that Arduino + HC-SR04 + blink example is the cheapest, quickest and easiest available solution. I guess that the tank is not in the proximity of the PC and you also have to deal with the USB 5 meters max cable length which it's not the case for a serial connection + usb to serial adapter.  

See here some USB distance sensors. They use serial over USB. As Chris commented, there is no simple USB interface to read pulses length.