Can I make a variable of a class into a function with JavaScript?

Question

Is it possible to make a variable "a" into a new class "simple". Then make a into a function so I can call a like 'a("hey")'? And if so how? Thanks!

class simple {
    /*
    function(c) {
        console.log(c);
    }
    */
}

let a = new simple();
let b = a('hey');