Backing up and restoring contacts with Time Machine on iMac

Yes, on both.

Time Machine (TM) automatically backs up your entire user folder, and that includes the data used by the Contacts app.

As an example, here’s how you would restore a deleted contact from TM:

1. Open the Contacts app.
2. With the app open and active, enter TM by clicking on the TM icon in the menu bar > Enter Time Machine.
3. You’ll should now see the TM interface layered with previous states of your Contacts app.
4. Use the timeline on the right to navigate to a backup before the contact was deleted.
5. Once you see the contact listed, select it, and click Restore.

To add to what Tesserax has stated if your contacts are in iCloud then TM will only go back about 24HRS. You will need to go to iCloud on the web to restore.

iCloud is not a backup for documents. Use TM. Also the contacts that iCloud has backed up is set by the OS and usually just shows the complete list that can be restored. In my iCloud I only see one list backed about a week ago so it does not keep a history of contacts.