$secretKey = "";
$response=file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret=".$secretKey."&response=".$_POST["g-recaptcha-response"]."&remoteip=".$_SERVER['REMOTE_ADDR']);
$responseKeys = json_decode($response,true);
if(intval($responseKeys["success"]) == 1) {
// Captcha onaylanınca yapılacak işlemler
}