Hi Dawood,
You can create unit costing for different types of orders.
See below link where it says how to create unit costing for sales order. Similarly you will find it for production orders, process order and so.
In the same screen you will find option to enter different kinds of item categories and post the value against them.
You will have to use a costing variant suitable for unit costing - as suggested by Srinivas in one of the above replies.
Thanks.