How to add the price indicator to the custom field in Magento?

I am developing a form to add additional attributes to the product. now I am searching for this functionality for a while, can you help me how to add an icon here?

like this.

 $fieldset->addField( 'amount', 'text', [ 'name' => 'amount', 'label' => __('Material Price'), 'id' => 'amount', 'title' => __('Material Price'), 'class' => 'required-entry validate-zero-or-greater validate-number', 'required' => true, ] );