how to deploy new f5 in one arm mode

Have a look on manual: BIG-IP Local Traffic Manager: Implementations: Configuring a One-IP Network Topology. The link is for sw version 11.6.0. For other sw versions search the corresponding manual.

If you are looking for one armed config where clients and servers are in the same subnet as well as the BIG-IP, you need to use SNAT to force return packets to be routed back via the BIG-IP.

Using SNAT is also pretty common for example when BIG-IP is deployed into an existing topology and one does not want to make topology/routing changes, especially for testing, PoC situations, server default gw pointing somewhere else than the BIG-IP, etc. In most cases one can simply use SNAT Automap.