have you tried timeOffRequests api ? .API response has a property called “senderMessage”, which is equivalent to the value of “note”.
senderMessage property is not mentioned in the documentation. you could check this in graph explorer.
GET /teams/{teamId}/schedule/timeOffRequests/{timeOffRequestId}
If the reply is helpful, please click Accept Answer and kindly upvote it. If you have additional questions about this answer, please click Comment.