Boards have been discussing if the capital campaign funds can be used for operating expenses during the COVID-19 crisis. If the capital campaign funds were restricted by a donor, then that restriction remains even during this COVID-19 crisis. You will need to contact the funder to see if they are willing to lift the restriction and allow you to use the funds for operating costs.
Usually funds are designated as capital campaign funds by the board, then, legally speaking, they are not truly restricted funds, they are board restricted funds, meaning you can shift the intention of those funds. If that is something you are considering, the board should discuss this and have a vote that is recorded in the minutes.