[{Text:" String is string",Text1:"string"},{Text:"Good is good",Text1:"good"},{Text:"Good is goodcase",Text1:"GoodCase"},{Text:"Good is goodcase",Text1:"GoodCaseNOMatch"}]

db.collection.aggregate([{$addFields:{matched:{$regexMatch:{"input":"$Text","regex":"$Text1",options:"i"}}}},{"$match":{matched:true}},{"$project":{matched:0}}])