doitinpoland.com/wp-content/plugins/mailchimp-for-wp/integrations/contact-form-7/admin-before.php

<p>
	<?php printf( __( 'To integrate with Contact Form 7, configure the settings below and then add %s to your CF7 form mark-up.', 'mailchimp-for-wp' ), '<input type="text" onfocus="this.select()" readonly value="' . esc_attr( '[mc4wp_checkbox]' ) . '">' ); ?>
</p>
	`<p>`
	`<?php printf( __( 'To integrate with Contact Form 7, configure the settings below and then add %s to your CF7 form mark-up.', 'mailchimp-for-wp' ), '<input type="text" onfocus="this.select()" readonly value="' . esc_attr( '[mc4wp_checkbox]' ) . '">' ); ?>`
	`</p>`