I'm on a MacBook Pro 2015 with Mac OS X 10.11.5 and InDesign CC 2015.4.
My Dimensions smart guide appear to be larger than yours. Notice the Dimensions rectangle is about the same height as the Selection tool on the Tools panel.
What hardware and software are you running? I don't know of a setting for that item in particular.
It looks like the same setup.
MacBook Pro (Retina, 15-inch, Mid 2015) - OSX 10.11.5 - InDesign CC 2015.4
I have looked for some time now, but cannot find the preference for the display.
Is your MBP connected to an external display?
Same problem here since the 11.2 update:
Also reported to Vineet from the ID Engineering Team in December 2015.
Edit: Mac Pro with 27"/2560x1440px display, OS X 10.10.5
It is a second display issue. I have a HP display connected (not retina), when it is unplugged the HUD is good. With the monitor connected, the HUD is unreadable.
I did send a bug report to Adobe.