A spiritual communion, recommended by the saints for centuries, is a prayer professing faith in Jesus presence in the Eucharist and inviting him to live in our hearts.
You make a spiritual communion by beginning with an examination of your conscience and making a good Act of Contrition. Then you pray one of the prayers recommended by the saints for inviting Christ into your heart.  Here is a prayer given to us by St. Alphonsus Liguori:

“My Jesus, I believe that you are present in the most Blessed Sacrament.
I love you above all things and I desire to receive you into my soul.
Since I cannot now receive you sacramentally, come at least spiritually into my heart.
I embrace you as if you were already there, and unite myself wholly to you.
Never permit me to be separated from you. Amen.”

As mentioned before, this type of communion can never replace receiving our Lord Jesus in Holy Communion at Mass, but it can help us to stay close to Jesus in this Most Blessed Sacrament of His Body and Blood in these extraordinary times.  Fr. Niccolls