Prestashop如何在订单页面下获取已发布的输入值？

I'm try to make a module

i have a hook hookDisplayBeforeCarrier here. I created a input

<input type="date" value="2017-02-14">

How can i get the this input value?

My codes:

public function hookDisplayBeforeCarrier()
    {

        $output = $this->context->smarty->fetch($this->local_path.'views/templates/frontend/delivery.tpl');

        return $output;
    }

Tpl file:

<div class="deliverydate">
        <p>  {l s='Select Delivery Date' mod='selectdeliverydate'} : <input type="date" value="2017-02-14"></p>
    </div>

First of all add name="your_variable" to the input tag.

To save its value you can add a button with this input and on clicking that button you have to send an ajax request to fetch its value and take appropriate action.

I hope this helps.