This depends on the technique you use to show the user's job title.
It would help if you could update your question with that detail.
In general, if you want to capture circumstantial data at creation, you may want to use a workflow that fires when an item gets created. Let that workflow discover the data items you want to capture, e.g. the user's job title, and then write that data to a list column that is used to store that data. If the workflow runs only when an item is created, then that's all you need. The data won't be changed if the existing item is updated.
Edit after comment: If you use a people column to show the person's job title, add a text column to the list and then use a workflow that writes the desired property of the people field to the text column when the item is created. That can be done in a SharePoint Designer workflow that kicks off when an item is created.