CMB in taxonomy

Ok, I’m sorry!
I used CMB2 in my website. In particular I create a custom post type call “prodotto”, and in it, I use a metabox image. Here is the code:

$cmb_demo = new_cmb2_box( array(
 'id'            => $prefix . 'sp_products_img_metabox',
 'title'         => __( 'Immagini prodotto', 'cmb2' ),
 'object_types'  => array( 'prodotto' ), // Post type
 'context'       => 'side',
 'priority'      => 'low',
 'show_names'    => true, // Show field names on the left
 // 'cmb_styles' => false, // false to disable the CMB stylesheet
 // 'closed'     => true, // true to keep the metabox closed by default
 ) );

    $cmb_demo->add_field( array(
 'name' => __( 'Thumbnail/Immagine principale', 'cmb2' ),
 'desc' => __( 'Carica l\'immagine principale del prodotto, verrà visualizzata più grande rispetto alle altre scelte sotto.', 'cmb2' ),
 'id'   => $prefix . 'prod_thumb',
 'type' => 'file',
 ) );

The result is wounderful and I succeed in it.
But if I want to display the same image in a taxonomy too, I can not do.
How is possible do?