What sensor I need for a guitar's project?

Other Hardware Sensors
1

I look this HC-SR04, but is too big.

Is there a sensor smaller than HC-SR04?

Or I need another type of sensor for a project like this?

Sorry for my english

2

What is the guitar's project?

3

the HC-SR04 is an ultrasonic distance sensor. What guitar-related application do you need a distance sensor for? Give us some more detail and I'd be happy to help.