BuddyPress.org

Hello,
You can use this plugin for showing the ID in the dashboard.

Show IDs by 99 Robots

and you may add following code to your theme’s functions.php to show the ID on user profile when the user is viewing his/her own profile or it is being viewed by the site admin.

/**
 * Show User ID on a user's profile to the profile owner or Administrator.
 */
function bidboy_show_displayed_user_id() {
	if ( bp_is_my_profile() || is_super_admin() ) {
		echo 'ID: ' . bp_displayed_user_id();
	}
}

add_action( 'bp_before_member_header_meta', 'bidboy_show_displayed_user_id' );

Best Regards
B