Wordpress custom admin page - Save Checkbox - php

Question

I am trying to create a custom page in the administration panel to save some checkboxes somewhere in an array so that later I can show them in the wordpress theme. But the truth is I am limited, I do not know how to continue to save that information, nor do I know if it is better to use update_option () or update_post_meta () to save that configuration.
I have the following code in the theme's functions file:
function wpdocs_unsub_add_pages() {
add_menu_page(
__( 'Unsub List', 'textdomain' ),
__( 'Unsub Emails','textdomain' ),
'manage_options',
'categoriasrelacionadas',
'wpdocs_unsub_page_callback',
''
);
}
/**
* Display callback for the Unsub page.
*/
function wpdocs_unsub_page_callback() {
echo 'Unsubscribe Email List';
?>
<form method="post"
action="<?php echo esc_html('?page=categoriasrelacionadas'); ?>">
<?php $cat_argtos=array(
'orderby' => 'name',
'order' => 'ASC');
$categorias=get_categories($cat_argtos);
foreach($categorias as $categoria) {
$args=array(
'showposts' => -1,
'category__in' => array($categoria->term_id),
'caller_get_posts'=>1
);
$entradas=get_posts($args);
if ($entradas) {
echo '<p>' .$categoria->name.
'<input type="checkbox"
name="categorias"
value="'.$categoria->term_id.'">
</p>';
}
}
?>
<?php
wp_nonce_field( 'acme-settings-save', 'acme-custom-message' );
submit_button();
?>
</form>
<?php
...
}
What else could I do to save the information and show the selected boxes?