Hopefully, I’m looking at your question from the right perspective. I’m assuming you mean tracking resource costs and labor hours in the same project schedule.
In order to forecast/track costs you’ll need to make certain that the resources have an hourly rate associated with them. In the Resource Sheet, add the Standard Rate column and enter the appropriate rate for each resource. Once this is entered, Project will automatically track costs, even though you may not see them in the standard views.
Next, open a Task Usage view. On the right hand side of the screen is the time scale data. The left column in this timescale data is the details column. Right click somewhere in the Details column. A popup list will appear with a few standard fields that can also be displayed in the timescale. If you want, click “Cost” and the timescale data will no include cost information. However, this cost field is only the costs associated with that specific timescale segment. If you want to see cumulative cost,, right click in the Details column again and this time click Detail Styles. This opens a new window that allows you to add more fields to the timescale display. On the left, scroll down to find Cumulative Cost. Select it, and then click the Show button to move it to the right side of the window. Click OK and now each timescale segment contains a running, cumulative cost. Doing this in a Task Usage type view will allow you to see cumulative costs at the project level, WBS levels, and individual task levels.
Hope that helps.