Wordpress - How to load the WordPress jquery in the <head> section
By default if you enqueue jquery then it gets added in header but if any plugin is changing the default behavior of it and adding it in footer instead of header then you can use the following code to alter it and force it to add in header again.
function insert_jquery(){
wp_enqueue_script('jquery', false, array(), false, false);
}
add_filter('wp_enqueue_scripts','insert_jquery',1);
For more information on wp_enqueue_script() function visit this page.