Save meta data with post, Without using any plugin [closed]

You can add custom meta fields for doing so.

Here, is sample code for adding a meta field for post type post. For more details please refer to link.

<?php

    /************************************************************************/
    function myPrice_meta_box()
    {
        add_meta_box('myPrice_field', 'Price', 'myPrice_meta_box_callback', 'post', 'normal', 'high');
    }

    add_action('add_meta_boxes', 'myPrice_meta_box');

    /**
     * Prints the box content.
     *
     * @param WP_Post $post The object for the current post/page.
     */
    function myPrice_meta_box_callback($post)
    {
        global $post;
        // Add a nonce field so we can check for it later.
        wp_nonce_field('myPrice_meta_box', 'myPrice_meta_box_nonce');
        /*
        * Use get_post_meta() to retrieve an existing value
        * from the database and use the value for the form.
        */
        $item_Price = get_post_meta($post->ID, '_price_', true);
    ?>
            <p class="order_id">
                <span>
                    <label>Price::</label> 
                    <input type="text" name="_price_" size="50" value="<?php echo $item_Price ?>" placeholder="Price">
                </span><br/>
            </p>
    <?php
    }

    /**
     * When the post is saved, saves our myPrice data.
     * @param int $post_id The ID of the post being saved.
     */
    function myPrice_meta_box_data($post_id)
    {   
        /*
        * We need to verify this came from our screen and with proper authorization,
        * because the save_post action can be triggered at other times.
        */
        /* Check if our nonce is set.*/
        if (!isset($_POST['myPrice_meta_box_nonce']))
        {
            return;
        }
        /* Verify that the nonce is valid.*/
        if (!wp_verify_nonce($_POST['myPrice_meta_box_nonce'], 'myPrice_meta_box'))
        {
            return;
        }

        /* If this is an autosave, our form has not been submitted, so we don't want to do anything.*/
        if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE)
        {
            return;
        }

        $price = isset($_POST["_price_"] ) ? $_POST["_price_"]  : '';

        /* Update the meta field in the database.*/
        update_post_meta($post_id, '_price_', $price);
    }

    add_action('save_post', 'myPrice_meta_box_data');
?>