https://hostname.example.com:2087/cpsess##########/json-api/modsec_is_installed?api.version=1

https://hostname.example.com:2087/cpsess##########/xml-api/modsec_is_installed?api.version=1

whmapi1 modsec_is_installed

{
   "data": {
        "data": {
            "installed": 1
        }
    },
    "metadata": {
        "version": 1,
        "reason": "OK",
        "result": 1,
        "command": "modsec_is_installed"
    }
}

<result>
   <data>
      <data>
         <installed>1</installed>
      </data>
   </data>
   <metadata>
      <version>1</version>
      <reason>OK</reason>
      <result>1</result>
      <command>modsec_is_installed</command>
   </metadata>
</result>