Undefined Variable error when passing in callback of rememberForever : Laravel 5.1

What I am doing ?

I pass CategoryID parameter value as default value to the where clause

public function SubCategories($CategoryID)
{
    $CandSubCat = \Cache::rememberForever('CandSubCat' . $CategoryID, function() {
        return \App\Models\Skill\Category_Model
            ::where("CategoryID", "=", $CategoryID)
            ->with("SubCategories")
            ->first();
    });

    return view("Skill.SubCategory.List", array("CandSubCat" => $CandSubCat));
}

Question:

Why it gives runtime error, saying:

Undefined variable: CategoryID in Where Clause?

via Chebli Mohamed