Well, you'll need an Arduino.
You'll need some means of detecting light levels. There are a number of different kinds of light detecting sensors.
You'll need something to move. You haven't said what that is.
You'll need some way to hold the thing to be moved.
You'll need some motivating device(s) to move whatever needs to be moved. This can be servos, stepper motors, solenoids, gear motors, pneumatic controls, hydraulic controls, etc. Depends on what fabrication skills you have, how you want to move whatever it is needs to be moved, and how heavy that thing is.
Some means of powering the Arduino and sensors would be useful.
A few wires to connect stuff together.
Some lights to indicate whether stuff is working might be good. If that includes LEDs, some resistors will be useful.
Diodes, transistors, etc. may be needed, depending on what you need to control. Maybe an H-bridge or motor controller.
Really, you've told us too little about your project or where you are or your skill levels for us to be putting together a shopping list for you.