Take the Field Data Type as
nvarchar(len)
where
len is the field length
prefix the value of the field with 'N' while inserting, like
strQuery = "INSERT INTO TableName( Col1, Col2, Col3) VALUES (" +
"\'" + Val1 + "\'," +
"\'" + Val2 + "\'," +
"N\'"+ val3 + "\')";
notice the N before the value of col3. as seen above,
in the above code segment,
Col3 has Unicode Text.