On Feb. 7, as rumors spread through the ranks of the Consumer Financial Protection Bureau that Elon Musk’s team had entered their building, federal workers took out their phones.

On high alert, they filmed unidentified young men from the team known as the Department of Government Efficiency being escorted by security through the glass doors of their downtown Washington headquarters. They shouted greetings from afar and tried to snap photos of their faces. Once the men were inside, one agency worker even confronted them in a conference room, demanding to see their credentials, in an incident described to The New York Times. One of the Musk aides used his laptop to block his ID badge from view.

As Mr. Musk and his associates have swept rapidly through government agencies, dismantling programs and seizing access to sensitive databases, some federal employees are pushing back — using whatever levers they have to resist the orders of the world’s richest man, both in public and behind closed doors.

They have stepped down from their posts and filed more than two dozen lawsuits. They have staged protests outside the federal buildings that Mr. Musk’s aides have penetrated and joined federal worker unions in droves. They have sent emails to hundreds of colleagues, blasting the new administration at the risk of their own livelihoods and careers. They have set up encrypted Signal chats, Zoom calls and Instagram accounts to share information and plan future actions.

During one video meeting with a representative of Mr. Musk’s team, civil servants at the technology arm of the General Services Administration even bombarded an online chat with spoon emojis to express their displeasure at the deferred resignation offer known as the “fork in the road.” (Their bosses responded by removing spoons from the list of searchable emojis permitted in their videoconferencing platform.)