Displaying admin notice dynamically

In that case wp_remote_get() will work fine.

Create a notice.php file and uploaded it on my server.

Then I have added these code into my plugin and it works for me.

<?php
$remote_data = wp_remote_get( 'http://example.com/notice.php' );
$remote_body = wp_remote_retrieve_datat( $remote_data );
?>

<div class="notice">
    <?php echo $remote_body ?>
</div>

Hope that helps.