Based on the mode of payment, you have the following options:
1. Credit Card (Stripe)
If you have Credit Card payments enabled via Settings -> Add-Ons, you can use the Charge Payment -> Pre-Authorize feature. This will block the amount on the user’s credit card for a maximum of 7 days (this may vary based on your merchant gateway and credit card type). In case of damage, you will need to use the Custom Entry button to add the damage amount and then charge the full amount of the invoice.
NOTE: At the moment this is for Stripe only. Get in touch with us if you need this feature for another gateway at firstname.lastname@example.org
2. Default Line Item (Recommended)
Create a Default Line Item for a Security Deposit by going to Settings -> Default Invoice Line Items and adding a Line Item of type Security (we recommend having the refund option enabled and the ‘included in Order total’ as unchecked).
You can then charge the Security Deposit separately as well as have it refunded on safe return of your equipment. Learn More on Security Deposits, Damage Waivers, and Refunds.