Can we enable HA between two different hardware?

From K8665: BIG-IP redundant configuration hardware and software parity requirements:

In BIG-IP 11.0.0 through 11.3.0, F5 does not support BIG-IP redundant configurationsthat run on different hardware platforms, as this configuration may detrimentally affect traffic management upon failover; the BIG-IP units in a redundant configuration must run on the same hardware platform. For example, if one BIG-IP system in a redundant configuration runs on the 3400 platform, the peer system must also run on the 3400 platform. Similarly, BIG-IP redundant configurations that run on virtual hardware must be configured with identical allotments of virtual resources.

Beginning in BIG-IP 11.4.0, F5 supports redundant devices in a device group on different hardware or virtual platforms through the load-aware failover feature. For more information about load-aware failover, refer to the Managing Failover chapter of the BIG-IP Device Service Clustering: Administration guide.