Collapsible Multi-Select UserForm Control

I would like to add a combobox type control that will allow multiple selections. I know that the combobox in the MS Forms Object Library only allows single selections and that the list box is the way to go to allow multiple selections, but I am trying to keep the form as small as possible. I would like to add a control similar to the one used on pivot charts, where the user clicks the dropdown box and can select multiple items. I'm hoping this control is installed with MS Office and just needs a reference to it, but I am open to installing third party controls as well.