It is just meta package which depends on xerions/exometer and configures some VM metrics like this:

system_info  port_count
system_info  process_count
system_info  thread_pool_size
statistics   run_queue
statistics   garbage_collection
statistics   io
memory       total
memory       processes
memory       ets
memory       binary
memory       atom
memory       atom_used
memory       maximum

xerions/metricman 
`--> xerions/exometer
     `--> Feuerlabs/exometer_core
          `--> basho/lager
          |    `--> DeadZen/goldrush
          `--> uwiger/parse_trans
          |    `--> uwiger/edown
          `--> eproxus/meck
          `--> boundary/folsom
          |    `--> boundary/bear
          `--> uwiger/setup
          |    `--> uwiger/edown
     `--> travelping/exometer_influxdb
          `--> Feuerlabs/exometer_core
          `--> benoitc/hackney
          |    `--> benoitc/erlang-idna
          |    `--> benoitc/mimerl
          |    `--> certifi/erlang-certifi
          |    `--> deadtrickster/ssl_verify_hostname

1. Add metricman to your list of dependencies in mix.exs:

   def deps do
       [{:metricman, github: "xerions/metricman"}]
   end

2. Ensure metricman is started before your application:

   def application do
       [applications: [:metricman]]
   end

3. Include the metricman configuration to your config.exs:

   try do 
       import_config "../deps/metricman/config/config.exs"
   rescue
       _  in _ -> :skip
   end

4. And you can add your own exometer reporter in your config.exs:

   config :exometer, :report,
       reporters: [
           {:exometer_report_graphite, [{:host, 'localhost'},
                                        {:port, 2003},
                                        {:api_key, 'exometer'}]}
       ]

   or for InfluxDB you can use conform config:

   influx.db = http://127.0.0.1:8086/default_db
   influx.tags = node:node_name,region:de
   

   See this for more information about configuring the reportes plugins.