Ah, OK, I misunderstood. A smoothed display is typical of a low resolution modelling program. ZBrushCore is a high resolution sculpting program. In order to get the best results from the sculpting brushes (other than the Insert Mesh type) you need to divide your model’s geometry using the Divide button in the Tool palette (Geometry sub-palette). Repeat the division until you’ve got the resolution you need. You can still edit the low resolution mesh, and any level in between, by moving the Tool>Geometry>SDiv slider up or down.
For DynaMesh, this is intended as a mid to low resolution feature to help you explore different shapes. Any time the topology becomes stretched you can re-DynaMesh. This will maintain an even topology which, when you are happy with the shape, you can then divide further for fine sculpting.