Monitoring is a critical component of all database administration. A firm grasp of MongoDB’s reporting will allow you to assess the state of your database and maintain your deployment without crisis. Additionally, a sense of MongoDB’s normal operational parameters will allow you to diagnose problems before they escalate to failures.
Following link contains available monitoring utilities for mongo and monitoring strategies are there are three methods for collecting data about the state of a running MongoDB instance:
First, there is a set of utilities distributed with MongoDB that provides real-time reporting of database activities.
Second, database commands return statistics regarding the current database state with greater fidelity.
Third, MongoDB Cloud Manager, a hosted service, and Ops Manager, an on-premise solution available in MongoDB Enterprise Advanced, provide monitoring to collect data from running MongoDB deployments as well as providing visualization and alerts based on that data.
As you are not interested in MMS (aka Cloud Manager),follow first and second methods and commands list for second mathod can be found in following link :
Database Command List for second method: https://docs.cloud.mongodb.com/reference/monitoring/
for the first you can select utilities like : ganglia,motop,mtop,munin,nagios,