Database
[{"name":"John Doe","userData":{"professions":[ObjectId("5f8ea4396586f1168ab3a298"),ObjectId("5f8ea4226586f1168ab3a296")]}},{"name":"John Smith","userData":{"professions":[ObjectId("5f8ea4396586f1168ab3a298"),]}},{"name":"Elon Musk","userData":{"professions":[ObjectId("5f8ea4466586f1168ab3a29a"),ObjectId("5f8ea4396586f1168ab3a298"),ObjectId("5f8ea4146586f1168ab3a295")]}}]
Query
db.collection.find({"userData.professions":ObjectId("5f8ea4396586f1168ab3a298")})