It isn't quite clear from your question if you are asking if you can take Lexapro (escitalopram) with HCl (hydrogen chloride), which is commonly used as a dietary supplement to improve digestion or with any other drug compound that contains HCl to form a drug salt compound (known as a hydrochloride salt form).
If you are asking about taking Lexapro with other drugs that contain the HCl to form a salt (more information on salt forms here: What Are Drug Salt Forms?) that is safe and you need only be concerned with the parent compound in terms of drug interactions. For example, Lexapro can interact with the over the counter cough medication dextromethorphan, which is available as the salt form, dextromethorphan hydrobromide. In general, we are concerned with dextromethorphan, not hydrobromide in regard to interactions as the amount of the salt used is often insignificant.
If you are asking about taking Lexapro with a HCl supplement, there is no data to indicate that there is an interaction. Most commonly, when HCl is used as a supplement, it is in the form of betaine hydrochloride (the hydrochloride salt form of betaine). Although betaine hydrochloride supplements provide betaine, an amino acid-like compound, they are usually used simply as a source for HCl.
Betaine hydrochloride supplements increase stomach acidity, and can certainly interact with some medications that are dependent on a certain stomach pH for dissolution and absorption. Fortunately, changes in pH don't appear to affect how Lexapro is absorbed. For this reason, it is recommended to be taken with or without food.