There is nothing that can be formally described as a '3D Sketcher' in NX. However, you can create so-called 'Associative Basic Curves' which can be created so that end points are associative to other curves and/or points and these can be 'rigged' in 3D space.
BTW, what version of NX are you running?
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA Siemens PLM: UG/NX Museum:
To an Engineer, the glass is twice as big as it needs to be.