This is the code and wiring diagram to build a distance sensor like the one placed on cars to facilitate parking, except these have no wires!
Arduino Nano
Display I2C
Radio Receiver
Radio Transmitter
JSN-SR04T(x2) waterproof ultrasound module
Buzzer
Slide switch
Led
C++
The part with the sensors and the transmitter must be installed like all the sensors that are sold, to the reversing lights. The part with the display instead, not being connected via wires, requires a power supply in the front dashboard of the car. For example it could be fixed in place of the radio, using batteries.