Passing value in form with amforms plugin
Whenever you submit forms to Craft, your name attribute must be formatted in a certain way by adding your values to a fields[] array. In your case, the field should look like:

&lt;input type="hidden" name="fields[nomDocumentEfficy]" value="my_value"&gt;

You can see this happening if you ever inspect a form field inside an entry in the CMS, or if you inspect the output generated by amforms' tags you're using: {{ form.displayField('email') }}

However, not all form field types get added to this array the same as a simple text or hidden field! For reference on how to format checkbox fields, date fields, or even Matrix fields, for example, you can reference this great guide on StraightUpCraft.