On Create Ticket page, when a repair problem is selected in the device details section, inventory part associated with that repair problem will automatically be displayed under Ticket Items.  If no part is associated with that problem you can do it yourself manually.

Under Ticket Items, add in the following details:

Repair Reference: Give reference of the repair problem in Device details with which you want to associate the inventory item.

Catalog Item: Select the part from the drop down or add a new one.

Supplier: Mention the supplier. This field is optional.

Stock: This will display the stock level of that part.

Warranty: This is the warranty of the part.

Status: If the part is used, faulty or broken.

Cost: The cost you have already set for the part

Tax: Select the tax class.

GST: This displays the calculated tax on the cost. You can set tax percentage in the settings.

QTY: The quantity of the parts that will be used.

Total: Displays the total price for the part

Once all details are entered, click Add Line Item to save the details or to add another job detail.