It typically works best on the CLO side to use surveys to capture this information.

Forms are created with an action type of Save Data. This allows you to gather data from constituents that can be downloaded as a CSV file. This is most commonly used for surveys and questionnaires. However, it does not directly update or create profiles in CLO. In order to do that, the creator needed to have used one of the two Constituent Profile forms:
The Create Constituent Profile Form - Allows constituent to create a new profile in Constituent360 through a Luminate CMS page.
The Update Constituent Profile Form - Allows constituent to update their profile in Constituent360 through a Luminate CMS page.
In the future, it may be better to use a different form type. Then you could pull the survey results directly from CLO.

There are also potential values that could pull the constituent and member IDs. If you were to add hidden fields, you could try these two variables to add as hidden field elements: ${cons.cons_id} & ${cons.member_id}.

For example, when editing the content of the form, click Hidden field. Then input, Name: constituent_id, Value: ${cons.cons_id}
However, none of it is very useful because it requires the user to log in. This is how it verifies the individual and is thus able to pull the IDs. Currently, the form does not require the user to log in before filling it out, and you may not want to have the person go through the hassle of logging in.

Another viable workaround is to download the results in CMS, upload them into a specific group in CLO, and then query that group, create a mail merge, and include the constituent and member IDs in the results. That would provide the necessary information for an offline database.