I've installed QtCreator in Kubuntu 15.10 through apt-get and it say my computer doesn't have the required Qt Kit and can be installed through Qt Maintenance Tool.
But I don't think I have Qt Maintenance Tool in my start menu and didn't found it in Synaptic.
Install Qt development packages qt5-default qtdeclarative5-dev through apt-get.
I found the maintenance tool binary for my installation at /opt/Qt5.7.0/MaintenanceTool on Ubuntu 14.04.
I found it by using the locate tool:
sudo apt-get install mlocate
sudo updatedb
locate -i maintenance | grep -i qt
Anyways, using the maintenance tool with the apt provided package was a rabbit hole with other problems. I ended up installing a fresh version of QtCreator from the universal linux binary install provided at qt.io installing into $HOME/Qt. Uses of that maintenance tool actually do work and I can upgrade Qt Versions easily.
Just add a Kit of your own choice in:
Tools > Options > Build & Run > Kits > (press) Add (button on the right side) > (give the Unnamed kit a name, or not, your choice) > Apply | OK
Note: The default kit, which comes pre-installed didn't work for me. So I recreated one.
You can select compiler kits, tools, platform, version of qt and anything else for your kit if you need to.
apt-get as by the OP, this answer only works for the Kit for desktop Qt development. Because that's the Qt version installed by apt. To develop for Android and the like, you need a Qt version compiled for Android. And that is only available within the Qt Maintenance Tool or when using the installer from the Qt website.