This is an advanced feature that requires you to write down and safe-keep an additional set of 12 words.
You will need an additional microSD card in order to create an ecrypted backup of your 24-word seed phrase, as well as a pen and paper.
Make sure that your Coldcard is unlocked with your PIN;
Insert the new microSD card into your Coldcard;
In your Coldcard go to "Advanced" > "Backup" > "Backup System";
Write down the 12 words in the order in which they are displayed on a piece of paper.
These words are unrelated to your 24-word backup.
In your Coldcard, go to "Advanced" > "Backup" > "Verify Backup".
This is useful for verifying that the backup file on the microSD card was not damaged or written incorrectly.
You must have at your disposition either a new Coldcard or one with no wallet generated (the Backup has been wiped from the device).
In your Coldcard, go to "Advanced" > "Backup" > "Restore from backup".
You will still need your passphrase to access your funds!