wehatecaptchas.php

<?php
$captchaVerification = !empty($_REQUEST["captcha_verification"]) ? $_REQUEST["captcha_verification"] : false;
if ($captchaVerification !== false) {
    $data = [
        "endpoint" => "verify",
        "captcha_verification" => $captchaVerification,
        "captcha_difficulty" => 5 // make sure the difficulty matches the diffulty you added to form button
    ];
    $options = [
        "http" => [
            "method" => "POST",
            "user_agent" => "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36",
            "header" => "Content-Type: application/x-www-form-urlencoded",
            "content" => http_build_query($data)
        ]
    ];
    $context = stream_context_create($options);
    $verify = file_get_contents("https://wehatecaptchas.com/api.php", false, $context);
    $response = json_decode($verify, true);
    $verify = $response["data"]["verified"];
} else {
    $verify = false;
}
?>