Method does not exist or incorrect signature: void put(OpportunityLineItem) from the type Map<Id,OpportunityLineItem>

Map<Id,OpportunityLineItem> mapOli = new Map<Id,OpportunityLineItem> ();
            for(OpportunityLineItemSchedule sch: lstLineItemSchedule) {
                If(mapOli .get(sch.OpportunityLineItemId) == null) {
                    Decimal oliUniPrice = oliIDToSalesPriceMap.get(sch.OpportunityLineItemId);
                    mapOli .put(new OpportunityLineItem(Id=sch.Id,UnitPrice =oliUniPrice));
                }
            }

mapOli.put(new OpportunityLineItem(Id=oLisch.Id,UnitPrice =oliUniPrice));

mapOli.put(<key- whatever you choose>, new OpportunityLineItem(Id=oLisch.Id,UnitPrice =oliUniPrice));