Submit form with route variable

I'm creating search form in laravel.

After form submit I want to get /search/{search_phrase} URL, i.e /search/cats

How do I create such URL in controler or by submitting form ?

I've tried for now (in controller) return view('search.index', ['search' => $search]); but this didn't worked.

I know I can pass variable this way: but this would be predefined variable and it is not working in this situation.

via Chebli Mohamed