Hi,

You can take a look on “Security code” form control (~\CMSFormControls\SecurityCode.ascx) which is used for document types, BizForms, custom tables etc.

Could you please let me know why do you need to use Captcha web part? It really makes sense to use this control for some web part or module and not alone. You can therefore simply integrate this control into your web part.

Best regards,
Miroslav Remias.