Wiring a receptacle from a ceiling box in a basement
Since this is a ceiling box the wiring is probably designed for a light fixture. As such it will have a neutral (which would be the white wires connected together, but it may have only a switched hot and not a line hot (which is always hot). But it is possible that it contains a line hot. The first task would be to find out if you have an always hot in the box.
With the wires connected as they were originally use your non-contact tester to see if the bundle of black wires is hot in all the wall switch positions. Also test the red wires. Record and report to us.
You say you want to use this box as a source for an &quot;outlet&quot; which I take to mean you want a receptacle to be powered with an always hot and a neutral from this box, right?
EDIT1
Use a pair of &quot;pigtails&quot; one white and one black to connect to a receptacle.  The white pigtail connects the bundle of connected whites to the neutral side of the receptacle (the longer slot); the black pigtail connects the bundle of blacks to the hot side of the receptacle (shorter slot). Unless this us a grounded receptacle in a metal box, use a green or bare pigtail to connect the ground wires to the ground screw of the receptacle.
EDIT2
To get maximum use of your wiring you should determine if the black and the red are part of a &quot;multi wire branch circuit&quot;.  You have said both are hot, but are these two wires switched by the same 2-pole breaker in your panel? Or are they each switched by one of a pair of linked (handle tied) 1-pole breakers in your panel?