<input value='' name="question" id="question"  class="form-
  control" placeholder="q">

<input value='' name="answer" id="answer" class="form-control"
  placeholder="a">

var inputQ = $('<input/>', {
        type: 'text',
        name: 'DynamicExtraField[]',
        placeholder: 'Вопрос',
        value: '',
        class: 'form-control'
    }).appendTo(div);

var inputA = $('<input/>', {
        type: 'text',
        name: 'DynamicExtraField[]',
        placeholder: 'Ответ',
        value: '',
        class: 'form-control',
        }).appendTo(div);

var question= $('#question').val();

var formValuesArray = [];
for(var i = 0;i<form.elements.length;i++){
  formValuesArray.push(form.elements[i].value); //Или то что нужно
}

$.post(
  "Url",
  $("#myForm").serializeArray();
  onCompleteCallback
);

<form id="form" method="POST" action="index.php">

  <input value='' name="question" id="question"  class="form-
  control" placeholder="q">

  <input value='' name="answer" id="answer" class="form-control"
   placeholder="a">

  <input type="submit" value="Отправить">

</form>

var inputQ = $('<input/>', {
    type: 'text',
    name: 'DynamicExtraField[]',
    placeholder: 'Вопрос',
    value: '',
    class: 'form-control'
}).appendTo('#form');

var inputA = $('<input/>', {
    type: 'text',
    name: 'DynamicExtraField[]',
    placeholder: 'Ответ',
    value: '',
    class: 'form-control',
    }).appendTo('#form');

$host = "localhost";
 $db = "test";
 $user = "root";
 $password = '12345';

 $data_base = new PDO ("mysql:host=$host;dbname=$db","$user","$password" );

 $data_base->exec("set names utf8");
 $data_base->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

// Подготавливаем запрос
$result = $data_base->prepare("
        INSERT INTO `table` (question, answer)
        VALUES (?, ?)
    ");
// Выполняем запрос
$result->execute( array(
    $_POST['question'],
    $_POST['answer']
) );

// Если произошла ошибка, уведомляем
if ( !$result ) {
   echo 'Error!';
   break;
}