[{_id:1,usages:2,word:"Name"},{_id:2,usages:1,word:"Street"},{_id:3,usages:1,word:"House"},{_id:4,usages:3,word:"Table"},{_id:5,usages:3,word:"Bread"},{_id:6,usages:4,word:"Door"}]

db.collection.aggregate([{$facet:{minUsages:[{$sort:{usages:-1}}],maxUsages:[{$sort:{usages:1}}]}},{$addFields:{lowestUsages:{$arrayElemAt:["$minUsages",0]},highestUsages:{$arrayElemAt:["$maxUsages",0]}}},{$project:{minUsages:{$filter:{input:"$minUsages",as:"minUsage",cond:{$eq:["$$minUsage.usages","$lowestUsages.usages"]}}},maxUsages:{$filter:{input:"$maxUsages",as:"maxUsage",cond:{$eq:["$$maxUsage.usages","$highestUsages.usages"]}}}}}])