The official docs show how to do this with ES6 component classes, but the same applies for stateless functional components.

Firstly, npm install / yarn add the prop-types package if you haven't already.

Then, add your propTypes (and defaultProps too if required) after the stateless functional component has been defined, before you export it.

import React from "react";
import PropTypes from "prop-types";

const Header = ({ name }) => <div>hi {name}</div>;

Header.propTypes = {
  name: PropTypes.string
};

// Same approach for defaultProps too
Header.defaultProps = {
  name: "Alan"
};

export default Header;

It isn't different with the stateful, You can add it like:

import PropTypes from 'prop-types';
Header.propTypes = {
  title: PropTypes.string
}

Here is a link to prop-types npm

It's done the same way you do with Class Based Components

import PropTypes from "prop-types";

    const = function_name => {}

    function_name.propTypes = {
       prop_name : PropTypes.number
       . . . . . . . . . . . . . .
    }

Hope This Helps !