Although it’s been called a “combination chart” for years, IMHO what you’re wanting to achieve is “layering” a second or multiple set(s) of data within a Chart “region” - to me, a Combo chart is really a comparative, relational method to overlay one set of data over another. Now, on to what you're likely looking for?! Screenshot pics attached, I used one of the "canned" templates to tweak as an example...
Set up a Chart as you normally would, in 2D (not 3D) with two data sets - the (1) axis labels and the (2) data to be plotted (using a Bar Chart as an example).
From the Data Menu, choose the Add Data Command and you’ll get the relevant Dialog Box.
Add data by either entering it manually or using the “Choose” option by clicking on the small icon in the Add Data Field within the Dialog Box. One can add additional data by holding down the Command Key if you’re using the Choose option; I chose only one group of data for simplicity.
Excel will present a second set of graphed items in a similar format to the original graphed items; change the formatting of either data set by clicking on the data set you want to change, and change its graph type - here, I chose to graph the added data into a line.
I then formatted the second Data Series by adding a secondary axis. Additional formatting can be added by adding a Data Label then formatting the label(s) to suit your preferences.