VPN is by definition private. It is Virtual Private Network. Depending on configuration it is a tunnel protected by encryption either from device you are using (computer, phone, tablet etc)(software client /server connection) or from router/VPN device that separate your local network (LAN) from Internet/Your ISP. (site to site connection)
In general encryption is very difficult to crack and unless you are involved in something really really bad not worth doing.
So. To answer your question ISP or your employer can not sniff your traffic and see what you are doing this way.
Still.. Employers do block VPN connections some times and if you do it on company equipment they could inspect it.

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