The VL6180X is a Time-of-Flight laser distance sensor by ST Microelectronics with a range of 20-200mm, at an accuracy of 1mm.
Datasheet can be found here.
A great example by Adafruit can be found here. Their library is compatible with this module. Pinouts are exactly the same.
Pololu also has a library for this available here, that supports scaling – allowing for greater range at lower accuracy.
This is the best sensor to use for the IEEE Arduino Green Arm Challenge.