How to Install MongoDb Exporter for Prometheus Monitoring in Kubernetes

I want to monitor my MongoDb with prometheus. I currently have my MongoDb deployed like this

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
  labels:
    app: mongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      containers:
      - name: mongodb
        image: mongo
        ports:
        - containerPort: 27017
        env:
        # These variables, used in conjunction, create a new user and set that user's password (From Mongo Docker Image)
        - name: MONGO_INITDB_ROOT_USERNAME
          valueFrom:
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-username
        - name: MONGO_INITDB_ROOT_PASSWORD
          valueFrom: 
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-password

and this service

apiVersion: v1
kind: Service
metadata:
name: mongodb-service
spec:
selector:
    app: mongodb
ports:
    - protocol: TCP
    port: 27017
    targetPort: 27017

And I installed prometheus via helm helm install stable/prometheus-operator

I know about this MongoDb Helm chart https://github.com/prometheus-community/helm-charts/tree/main/charts/prometheus-mongodb-exporter. But to my understanding, this installs MongoDb and the MongoDb Exporter, so because I have MongoDb already setup, this is of no use for me, right?

What are the steps to install only the Mongo Exporter and connect it with my Mongo Database? All I know is, I need to create a ServiceMonitor that has a label of release: prometheus-operator-1602753506.

Sorry for this beginner question, I'm still very new to kubernetes and helm, so I'm quite confused at this point