Database
[{"_id":ObjectId("5e786534018df110a7a2a92f"),"timeStamp":1584948532188.0,"value":2124},{"_id":ObjectId("5e786534018df110a7a2a930"),"timeStamp":1584948532288.0,"value":231},{"_id":ObjectId("5e786534018df110a7a2a931"),"timeStamp":1584948532387.0,"value":4567}]
Query
db.collection.aggregate([{$match:{timeStamp:1584948532188.0}},{$group:{_id:null,maxVal:{$max:"$value"}}}])