Could I use the stereo mix in the laptop as sound sensor for arduino?

I want to make reactive LED strip without buying sound sensor, so I want to use the built in stereo mix as sound sensor to make the LEDs reactive

Please read the first topic telling how to get the best from this forum.
Your post gives no clue, makes no sense.

Are you asking if you can get the sound from a laptop into an Arduino? Yes there are ways to do that provided the laptop has a headphone output or equivalent. Not all do.