$captcha;
if(isset($_POST['g-recaptcha-response'])){
          $captcha=$_POST['g-recaptcha-response'];
}

if(!$captcha){
  echo "CAPTCHA NULL";
  exit;
}

$response=json_decode(file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret=6Ld65gYTAAAAANnz1olMsUH2-SdWJOfB_ztlvOrF&response=".$captcha."&remoteip=".$_SERVER['REMOTE_ADDR']), true);
if($response['success'] == false)
{
  echo "CAPTCHA WRONG";
}else
{
  echo "CAPTCHA RIGHT :)";