On the back side of the nRF52840 Dongle, there are connection points for the SWD interface.
The dongle is equipped with a footprint for two different connectors. On footprint P1, a standard 2×5-pin pin header with a 1.27 mm pitch can be soldered. On footprint J2, it is possible to connect a TC2050 cable from Tag-Connect.
Figure 1. SWD interface connectors
For instance, a Nordic development kit can be used as a programmer for the Dongle.